Objective: To study how physicians from the admitting department reason during the decision-making process to forego life-sustaining treatment of patients in intensive care units (ICUs).Design: Qualitative interview that applies a phenomenological approach.Setting: Two ICUs at one secondary and one tertiary referral hospital in Sweden.Participants: Seventeen, admitting-department physicians who have participated in decisions to forego life-sustaining treatment.Results: The decision-making process as it appeared from the physicians' experiences was complex, and different approaches to the process were observed. A pattern of five phases in the process emerged in the interviews. The physicians described the process principally as a medical one, with few ethical reflections. Decision-making was mostly done in collaboration with other physicians. Patients, family and nurses did not seem to play a significant role in the process.Conclusion: This study describes how physicians reasoned when confronted with real patient situations in which decisions to forego life-sustaining treatment were mainly based on medical-not ethical-considerations.